“There are a lot of species out there that are overlooked, and when you get to know them they’re just as energetic and beautiful as the ones we’re familiar with,” says Gumbs. According to the EDGE2 metric, the mountain pygmy possum, a tiny marsupial found in the wild across several square kilometers of Australia’s Victorian Alps, should be our highest priority mammal. Of the mammals for which we do not have good preservation data, the largest mammal is the long-eared hedgehog, a relative of hedgehogs found mainly in Laos. EDGE ratings were also calculated for amphibians, birds, corals, reptiles, sharks, rays, and gymnosperms, a plant group that includes conifers and cycads.
Thinking about animals in terms of their evolutionary distinctiveness has come into play. The EDGE metric was one of the indicators chosen for the post-2020 Global Biodiversity Framework—a major biodiversity agreement adopted by the UN in December 2022. The group that redlists species at risk, the International Union for Conservation of Nature , together. of Nature, too, has a phylogenetic diversity task force, of which Gumbs is vice-chair. One growing focus, Gumbs says, is protecting entire ecosystems that preserve many evolutionarily diverse plants and animals rather than focusing on individual species.
Of course, evolutionary specificity is only one way to think about conservation priorities. Groups that decide which projects to fund, where to place protected areas, and which species to target tend to consider a wide range of factors before making any major decisions. But the EDGE2 metric finds something interesting, says Rafael Molina Venegas, professor of plant biodiversity at Universidad Autonoma de Madrid in Spain. If you think of all the species out there as unique books, then specific evolutionary species are like very old unique tomes of which there are only a handful of copies. If you lose these rare species, part of the world’s evolutionary history is gone forever.
And there is another reason to care about evolutionary specificity. Molina Venegas’ work has found that if we choose plant species based on their evolutionary uniqueness, more plant species useful to humans would be protected than if we took a random approach to picking species. In other words, achieving uniqueness appears to be a practical way to think about the species to be protected.
One way to think about the EDGE metric is to imagine armageddon. A rogue asteroid is a year away from destroying Earth. Fortunately, scientists have identified a completely empty Earth-like planet somewhere else in the Universe. All we have to do is decide which species we want to cram onto our spaceship and take to the new planet. Evolutionary specificity might not be a bad starting point, says Molina Venegas. That way you would bring a wide variety of creatures, each with a unique function on the new planet. “It is hoped that they will complement each other in the new ecosystem in which they will have to grow,” he says.
In many ways humans are enacting a slow-motion armageddon on Earth’s biodiversity. We don’t have to fix the spaceship yet, but we do need to think carefully about the tools we have to stop the loss of irreplaceable species. We have tools like scientific research, gene banking and conservation areas. The way we think about biodiversity is also a vital tool. Everyone wants to save the animals, but we live in a world where species are competing for limited conservation resources and against the rapid expansion of humanity. If we don’t make tough decisions about which species to protect, the math doesn’t add up.